Drop hammer



March 6, 9 F. RIEMENSCHNEIDER DROP HAMMER 3 Sheets-Sheet 1 Filed June12, 1952 INVENTOR: Fk/Tz E/EMENSYHNE/DEE,

DROP HAMMER Filed June 12, 1952 3 Sheets-Sheet 2 I N V EN TOR. f2! TZEIEAM'NSOWVE'IDEB H S HGE/YTS.

March 6, 1956 F. RIEMENSCHNEIDER 2,737,066

DROP HAMMER Filed June 12, 1952 5 Sheets-Sheet 5 FRITZ izlemeflscwaofe,

HIS AGENTS.

United States Patent DROP HAMMER Fritz Riemenschneider, LeverkusenSchlebusch, Germany, assignor to Eumuco AWG. fiir Maschinenbau,Leverkusen-Schlebusch, Germany, a German corporation Application June12, 1952, Serial No. 293,174 Claims priority, application Germany June14, 1951 1 Claim. (Cl. 78-3l) The invention relates to drop hammers andrelates more particularly to drop hammers of the type wherein the hammerhead is suspended from a flexible chain.

Desirable features for a drop hammer include the development of suitabledrop energy by the hammer head, and this is generally speaking wellaccomplished by such machines now in use. However, present drop hammersare deficient therein that they have too great a length of fall, usuallyof up to 7 feet or more, which brings about that only low dropfrequencies can be had.

It is among the principal objects of the instant invention to provide adrop hammer with a high drop frequency, having a comparably great weightof hammer head and a smaller length of fall.

In order to increase the drop frequency, it is desirable to arrange forspeedy lifting of the hammer head. At the same time, owing to the greatweight of the head, it is advantageous to keep the lifting power withinreasonably low proportions. For this purpose, particular liftingmechanism is arranged which comprises a specially shaped lifting cam, aswill be more fully explained hereinbelow.

With the above and other objects of the invention in view, the inventionconsists in the novel methods, construction, arrangement and combinationof various devices, elements and parts, as set forth in the claimhereof, one embodiment of the same being illustrated in the accompanyingdrawings and described in the specification.

In the accompanying drawings,

Fig. l is a front elevational view, partly in section, showing a drophammer in accordance with the invention;

Fig. 2 is a sectional view taken on line 22 of Fig. 1;

Fig. 3 is a sectional view taken on line 33 of Fig. 1;

Fig. 4 is a large scale elevational view of the lifting cam shown inFig. 1 but, for the sake of clarity and simplicity, showing the cam inplain outline; the cam is illustrated in position before lifting;

Fig. 5 is an elevational view similar to Fig. 4, but showing the camafter slightly more than a one-quarter lifting turn;

Fig. 6 is a fragmentary elevational view of a lifting chain inaccordance with the invention; and

Fig. 7 is a sectional view taken on line 77 of Fig.. 6.

In carrying the invention into effect in one of the embodiments whichhas been selected for illustration in the accompanying drawings and fordescription in this specification and referring now particularly toFigs. 1 and 2, there is provided a drop hammer generally indicated at 11which has a base 12 and an anvil 13 arranged thereon. A lower die 14 isexchangeably secured to the anvil 13. Two upright legs 16 and 17surmount the base 12, each having a guide 18 for guiding therebetween ahammer head generally indicated at 19.

The hammer head 19 has on its lower side an upper die 21 that isinterchangeably secured to the head 19, and is in registry with thelower die 14.

A bridge 22 is supported by the legs 16 and 17' and carries a mechanismgenerally designated 23 for lifting, holding and respectively releasingthe hammer head 19.

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A lifting chain 24 is interconnected to the hammer head 19 and to themechanism 23. The chain 24, as best shown in Fig. 2, carries on itslower end a rod 26 that protrudes to the interior of a chamber 27 thatis formed on the interior of the hammer head 19. The rod 26 has on itslower end a mushroom-shaped enlargement 28 that is normally disposedabout midway of said chamber 27 and is spaced above the bottom of saidchamber 27. Said enlargement 28 supports a disc 29 which, in turn,supports a resilient material 31, such as several layers of rubber sheetor the like, within said chamber 27. A platen 32'covers the top of thechamber 27 thereof, and provides an abutment for the resilient material31, preventing removal of the resilient material upwardly from thechamber 27. The platen 32 is removably secured to the head 19, forinstance, by means of a key 33, as shown in Fig. 1, and has a centralopening 34 for the rod 26, and the opening 34'is wide enough to permitsideward swinging movement of the rod 26.

The lifting mechanism 23 comprises a lifting cam 36 that is secured to ahorizontally disposed rotatable shaft 37. The upper end of the linkchain is secured to the lifting cam 36 at an attachment point 38thereof.

The length of fall of the drop hammer in accordance withthe'invention isabout fifty-one (51) inches, and in a preferred embodiment is only aboutthirty-nine (39) inches. Accordingly, in the preferred embodiment, thecircumference 39 of the'cam 36 which preferably corresponds to thelength of fall, has a rectified length of thirty-nine inches. Duringlifting, the chain 24 is wound up on said circumference 39.

The said shaft 37 that carries the cam 36 is rotatably journalledinanti-friction bearings 41 which are supported in the bridge 22. Saidshaft 37 carries on one side a brake, generally indicated at 42, and onthe other side a'clutch, generally designated 43. The brake 42 includesa stationary part 44 which is supported on the bridge 22, and a movablepart 46 that is keyed to the shaft 37. Means are provided, for instance,one or more springs 47 operable to normally interengage the movable part46 with the stationary part 44, to hold the shaft 37 normally still.There are provided release means such as hydraulic means (not shownindetail) fed by a hydraulic conduit 48, to release the brake to permitrotation of the shaft 37.

The said clutch-43 comprises a single inner lamella 49 that is keyed to,and rotatable with, the shaft 37, and two outer lamellae 51 and 52, oneon each side of the lamella 49. Said outer lamellae 51 and 52 arerotatable about the axis of the shaft 37 and furthermore are movable inopposite directions axially of the shaft 37 for releasable frictionalengagement of the inner lamella 49 of the shaft 37. Said outer lamellae51 and 52 are dis posed in a housing 53 that is rotatably journalled, bymeans of a journal bearing 54 on the shaft 37, so that rotation of thehousing 53 and frictional interengagement of the lamellae 59, 51 and 52will cause rotation of the shaft 37. A plunger 56 is provided which isreciprocably movable axially of the shaft 37 to actuate, and to release,the movable lamellae 51 and 52, and which is actuable by means ofapneumatic mechanism generally indicated at 57.

The rotatable'housing 53 carries cooling fins 58 and is provided'on its'outer circumference with gear teeth 59 that mesh with a pinion 61. Saidpinion 61 is mounted on a shaft (not shown) coaxially with a pulley 62that is driven by means of a plurality of belts 63 from a motor 64. Themotor 64 and the shaft carrying the pinion 61 and the pulley 62 aresupported on the bridge 22. Means, such asdogs' 66, may be provided forcontrolling the pneumatic circuit 67 for the mechanism 57 and theconduit 48, and means, suchas a pedal 68, may be provided to actuof theconduit 67 are well known, and therefore not described in full detailherein. 1

The cam 36 has eccentrically arranged an opening 71 with which it ismounted on the shaft 37, and keyed thereto at 72 and 73. Thecircumference 39 includes a section between the points A and B that isconcentric with the center C of the opening 71, and the said center Ccoincides with the axis of rotation of the shaft 37. Between the pointsB and D on the circumference 39, the radii from the center C increasecontinuously, and between D and E decrease again. The are between B andE may be circular and described about a center point F which is disposedon the line BCD and spaced thereon from the center C. Accordingly, whenthe lifting cam 36 rotates in the direction G from the initial positionshown in Fig. 4, towards the position in Fig. 5, it has moved about thecenter C for an angle H somewhat in excess of a right angle; throughoutthe rotation for the angle H, the speed of lifting of the chain 24 willbe linearly proportional to the angular speed of the cam 36 as itrotates about the center C. As best shown in Fig. 5, the chain 24 willafter the rotation for the angle H make contact with the point B on thecircumference 39. Between the points Band D, it will be noted, thelifting speed of the chain 24 will be increased as compared to the speedbetween A and B assuming continued steady angular rotation of the shaft37, and thereafter, between D and E, the lifting speed of the chain 24will again be decreased as compared with the speed between B and D. Thecam 36 may have holes (see Figs. 4 and 5) to reduce the weight thereof.As mentioned before, the circumference 39 is so dimensioned, that duringlifting the length of chain available for lifting will be entirelyrolled-up on the circumference 39.

In accordance with a preferred embodiment, a special chain 24 may beprovided, shown in Figs. 6 and 7. It comprises inner links 74, andpaired outer links 76 as well as connecting bolts 77 and nuts 78. Eachinner link 74 comprises a bar 79 that has on both ends opposite integralbosses 81. Each boss 81 rests in a matching cavity of an outer link 76,in order to take up the stress, thereby relieving the bolts 77 of anyshearing stress. Each of the outer links 76, furthermore, is providedwith recesses 83 to reduce the weight thereof.

The operation of the drop hammer is as follows.

The motor 64 is started, and will turn the pulley 63, which will rotatethe pinion 61 and, by means of the gear teeth 59, rotate the housing 53.The spring 47 will actuate the brake mechanism to hold at standstill theshaft 37.

Operation of the pedal 68 will actuate the circuit 67, and thereby thebrake 42 will be released, against the action of the spring 47, and atthe same time the plunger 43 will actuate the clutch 43. Thereupon, thelamellae 51 and 52 will frictionally engage, and turn, the lamella 49,thereby rotating the shaft 37. The lifting cam 36 will rotate with theshaft 37, and will lift the link chain 24. The rod 26 will thereby pressupwardly against the disc 29, the pressure thereof will be taken up bythe resilient means 31 and by the platen 32, and the hammer head 19 willbe lifted, sliding between the guides 18.

The lifting impact between the chain 24 and the head 19 will be gentle,owing to the take-up of the pressure by the resilient means 31. Theshaft 37 will rotate at uniform speed; however, the lifting of the chain24, due to the shape of the circumference 39 of the cam 36 will first beslow, thereafter be accelerated, and thence be decelerated beforereaching the end of the upward stroke. The lifting will be completedafter a single turn of the cam 36.

Upon reaching the upper extreme position, the head 19, by means of theupper dogs 66, will actuate the circuit 67, so that the flow ofcompressed air to the brake 42 and to the clutch 43 is cut-off, andinstead these parts are opened to the atmosphere. Thereupon, the brake42 will be actuated by the spring 47 arresting the rotation d of theshaft 37, and the plunger 56 will release the lamellae 51 and 52,uncoupling thereby the clutch 43. The motor 64, the pinion 61 and thehousing 53 will continue to turn idling.

If a fall of the hammer head 19 is desired, the brake 42 will bereleased by the operators by supplying compressed air through theconduit 48. Thereafter, the hammer head will descend under its ownweight, releasing its energy to a workpiece that may be held between thedies 14 and 21. The combined small length of fall and great weight ofthe hammer head 19, will release a large energy onto the work piece.Near the end of the downward stroke of the hammer head 19, it may, ifthe machine is so set, actuate the lower dog 66 to initiate the liftingstroke. Instead of such automatic regulation, a regulation of the upwardand downward stroke succession may be arranged for hand or footoperation.

Owing to the short length of fall, a high drop frequency can beattained, which, for instance during drop forging, enables an excellentutilization of the heat within the work piece. This makes it possible touse dies suitable for pre-forging as well as for finishing forging,obviating the use of separate special dies for each operation.

At the end of the descent of the hammer head 19, the rod 26 will for ashort distance, proceed downwardly within the chamber 27 in the freespace formed below its normal position, and will thereby avoid anyimpact damage to the links of the chain 24.

Certain of the advantages of the invention have already been hereinreferred to. It may be useful, however, to allude particularly at thispoint to the advantage provided by the shape of the cam 36, whichenables the developing of the necessary lifting acceleration for thechain and hammer head without the necessity for excessive power to drivethe cam. This also helps to keep the dimensioning of the clutch 43within reasonable limits.

It will be apparent to those skilled in the art that the novelprinciples of the invention disclosed herein in connection with specificexemplifications thereof will suggest various other modifications andapplications of the same. It is accordingly desired that in construingthe breadth of the appended claim it shall not be limited to thespecific exemplifications of the invention described herein.

Having thus described the invention, what I claim as new and desire tobe secured by Letters Patent, is as follows:

In a drop hammer, in combination, a frame defining a guide way, a hammermovable in said guide way and a mechanism for lifting said hammer headcomprising power means and a cam supported by said frame, a clutch andbrake operatively connected between said power means and said cam fordriving the cam through one revolution and releasing the same, means foractuating and for releasing said brake and clutch, an elongated flexiblelifting means connected at one end of said hammer and at the other endto said cam, said lifting means being adapted to be carried around thecircumference of said cam when the same is used for lifting the hammer,and said cam having a circumference for receiving said lifting meanswhich includes a minor first portion concentric with the axis ofrotation of said cam, an adjacent second substantial portion havingincreasing radii from said axis and a third minor portion havingdecreasing radii from said axis whereby the lifting of said hammer isstarted at a uniform speed, then an accelerating speed through the majorpath of travel of said hammer and then a decelerated speed prior torelease of said hammer.

References Cited in the file of this patent UNITED STATES PATENTS463,574 Hammesfahr Nov. 17, 1891 629,737 Bassett July 25, 1899 1,324,925Rice Dec. 16, 1919 1,614,419 Brewster Jan. 11, 1927 1,720,592 FitzgeraldJuly 9, 1929

